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New Engine design and configuration

shiv.brahmi

Website User
Non-VOC Member
Hello Everyone,

I am trying to build a new 50 degree v-twin engine using as many custom Royal Enfield Parts as possible, but basing the design on the Series "A" Rapide (I am aware of the fact that the Seriies a was less than 50 degrees), to be honest the only reason is that I cannot hope to buy one, which means that I will get the following off the shelf of any Royal Enfield Dealre in India

- Cylinders
- Pistons
- Heads
- Carburators (Preferably will try to source a Kehin 28mm for wach cylinder)
- Hydraulic tappits
- etc....

The problem I am facing is with the timing chest .. I can re-design the entire engine case and will keep the oiling lines outside the casing on purpose to further the vintage look but have no idea on what the timing gear ratios are .. plus to add to that in a standard RE the pushrods are parallel to each other versus them being alligned in a "V" formation which actually increases the problem .. I will try to mill out the head and the bore to accomodate the "V" design .. to decrease friction and increase performance however still need help in term of the calculations for the gears for the timing chest .. can anyone help - (FYI .. the bore and stroke are the same for the RE and the Rapide)
 

shiv.brahmi

Website User
Non-VOC Member
Hello Guys,

Thank you, I am aware of the "Musket" and the "Carberry" Enfields, both are pretty ambisious projects and they use the cast iron barrels versus the AVL design alloy barrels and design as a base, I am more intrested in using and developing the AVL engines as a base and the timing gear ratios of the Vincent Black Shadow, purpose to get something as close to the Black Shadow as possible, in terms of the engine at the very least.

I have plans of actually cutting up the barrel's oil return and make the pushrods visible etc. the tapits these guys have used are basic old design and I plan on using the hydraulic tapits from the new enfield 500 classic .. I will post the design specs here shortly .. plus the rockers that these engines have are stock RE rockers .. I am using ones from a v4 engine .. similar in design to the Vincent's (comes off an old indian car make) .. to reduce friction and increase output .. basically when I am done the engine will largely bear no resemblence to the RE ..

I apologize if I have been unclear.

All advise is welcome.. Best regards
 

shiv.brahmi

Website User
Non-VOC Member
The crank can be borrowed from a RE .. as the only thing different will be the crank pin .. given that .. if memory serves me correctly .. the Vincent does not have intersecting fork type of a connecting rod set-up like the Harleys' they are independent of each other and located side by side ... minor issue I believe .. I might be wrong though
 

timetraveller

Well Known and Active Website User
VOC Member
Interesting that you can use the standard flywheels, main shafts etc. On Vincents the balance factor is very different between the twins and singles. 46% on the twins and 60-65% on singles. You are correct that Vincents do use side by side connecting rods on the crank pin with a hardened steel spacer between them. Good luck with the project.
 

shiv.brahmi

Website User
Non-VOC Member
Thank you

Interesting that you can use the standard flywheels, main shafts etc. On Vincents the balance factor is very different between the twins and singles. 46% on the twins and 60-65% on singles. You are correct that Vincents do use side by side connecting rods on the crank pin with a hardened steel spacer between them. Good luck with the project.

Hello Timetraveller,

Thank you, these are thing s that i am bit shoddy at, will keep this in mind, I do have help in terms of a few RE gurus ... appreciate you giving me a heads up here .. what I am at this time most concerned about is the timing chest .. I have no Idea of the timing gear specs .. can you help with that .. again .. I am looking at the Series A specs ..

Best Regards,

Shiv
 

sidmadrid

Well Known and Active Website User
VOC Member
You will struggle to obtain information.They only made 80 series A rapides, between 1937- 1939. It was 70 years ago, how many have survived?
The Vincent Owners Club has a series 'A' section and the organiser of that section may be able to help, he may have blueprints of the engine, but he may not. Join the club and find out, ...well worth the money.
P.E.Irving was instrumental in designing the engine, he wrote the book 'Tuning for Speed', many of the design features of that engine are alluded to in the book, it is an essential read.
The series 'A' is, as you know, an interesting engine, described as 'a plumbers nightmare' and 'an engineering solution looking for a question'.
I would dearly like to own one.
I have a degree in mechanical engineering, am a chartered engineer, and a fellow of the institution, I also have a machine shop to die for, but I would hesitate to go down the road you wish to travel.
good luck

Just had a thought, this isnt an April Fool thing is it Shiv??
 
Last edited:

shiv.brahmi

Website User
Non-VOC Member
You will struggle to obtain information.They only made 80 series A rapides, between 1937- 1939. It was 70 years ago, how many have survived?
The Vincent Owners Club has a series 'A' section and the organiser of that section may be able to help, he may have blueprints of the engine, but he may not. Join the club and find out, ...well worth the money.
P.E.Irving was instrumental in designing the engine, he wrote the book 'Tuning for Speed', many of the design features of that engine are alluded to in the book, it is an essential read.
The series 'A' is, as you know, an interesting engine, described as 'a plumbers nightmare' and 'an engineering solution looking for a question'.
I would dearly like to own one.
I have a degree in mechanical engineering, am a chartered engineer, and a fellow of the institution, I also have a machine shop to die for, but I would hesitate to go down the road you wish to travel.
good luck

Just had a thought, this isnt an April Fool thing is it Shiv??

Thank you Sid,

LOL .. Well I can assure you of one thing this is all heart .. not an April fool's thing .. for me this is a long term project .. pouring money and time and effort into it as I go along and as and when I have enough to spare .. I have a thing for the Vincent Series A .. gather it's more to do with the fact that it's not unit construction .. and the shimmer of the copper lines etc.. I am not an engineer have a hotel management degree that's not quite worth anything right now cuz I work as a BD manager .. But I believe that it can be done .. and obviously .. I will be refining and making mods . the primary aim is to get it to fire and not blow-up so there are some things I will not trust my mods to .. wish me luck and please do help me with any advise you can .. I always appreciate it ..

Thanks again .. Best Regards,

Shiv
 

vince998

Well Known and Active Website User
VOC Member
Hello Everyone,

I am trying to build a new 50 degree v-twin engine using as many custom Royal Enfield Parts as possible, but basing the design on the Series "A" Rapide (I am aware of the fact that the Seriies a was less than 50 degrees), to be honest the only reason is that I cannot hope to buy one, which means that I will get the following off the shelf of any Royal Enfield Dealre in India

- Cylinders
- Pistons
- Heads
- Carburators (Preferably will try to source a Kehin 28mm for wach cylinder)
- Hydraulic tappits
- etc....

The problem I am facing is with the timing chest .. I can re-design the entire engine case and will keep the oiling lines outside the casing on purpose to further the vintage look but have no idea on what the timing gear ratios are .. plus to add to that in a standard RE the pushrods are parallel to each other versus them being alligned in a "V" formation which actually increases the problem .. I will try to mill out the head and the bore to accomodate the "V" design .. to decrease friction and increase performance however still need help in term of the calculations for the gears for the timing chest .. can anyone help - (FYI .. the bore and stroke are the same for the RE and the Rapide)

Hello Mr Brahmi. Greetings to India.

The ratios for the timing chest on a 4 stroke engine are relatively simple.

The Cams (and ignition) have to travel at 1/2 crank speed.
whatever pinion (number of teeth) you use on your crank mainshaft, the cam pinions (and ignition)have to be twice the size to travel at half the speed. (try to use even numbers as this keeps things simple)

If you can drive cam and ignition off the mainshaft pinion, all well and good. If this doesn´t fit in with your design, then you will have to use a so called idler pinion. It does not matter what size this is as the ratio is calculated from drive to driven gear. Your single idler is in between so will not influence the ratio.

Hope this helps.
 

shiv.brahmi

Website User
Non-VOC Member
Hello Mr Brahmi. Greetings to India.

The ratios for the timing chest on a 4 stroke engine are relatively simple.

The Cams (and ignition) have to travel at 1/2 crank speed.
whatever pinion (number of teeth) you use on your crank mainshaft, the cam pinions (and ignition)have to be twice the size to travel at half the speed. (try to use even numbers as this keeps things simple)

If you can drive cam and ignition off the mainshaft pinion, all well and good. If this doesn´t fit in with your design, then you will have to use a so called idler pinion. It does not matter what size this is as the ratio is calculated from drive to driven gear. Your single idler is in between so will not influence the ratio.

Hope this helps.

Hello Vince998, Greetings and fair tidings to Germany as well ..

Thank you ever so much for pointing me in the right direction, I've been having sleepless nights over this and now I understand why this information is not to be found anywhere .. probably on account of the fact that it is oh!! so plain a piece of information .. I feel so dumb right now .. but this will be something that I shall never forget .. again Sir appreciate your help .. I am going to begin my CAD drawings .. and will be sharing them if anyone is interested.

Warm Regards,

Shiv
 

timetraveller

Well Known and Active Website User
VOC Member
Hi Shiv. I am not familiar with the inner working of an Enfield timing cover, cam and follower layout etc. However I do use ACAD so if you are prepared to email me either .dxf or .dwg files I should be able to read them and make some comments. I normally work in 3D but if all you have is 2D stuff then I should be able to see enough from that to be able to comment as to which way it might be useful for you to go. Contact me on enw07@btinternet.com
 

shiv.brahmi

Website User
Non-VOC Member
Hello Timetraveller,

Appreciate this offer, the RE factory once it had shifted to Madras (now Chennai) india had lost the blueprints of the RE 350 and other models long before my tim eand as far as I know there are no existing blueprints or cad drawings of the engine, I am however in the process of drawing these in 2D soon once I have finished .. I will share these with you ..

Appreciate your help .. will keep you posted on the developments ..

Warm Regards,

Shiv
 

shiv.brahmi

Website User
Non-VOC Member
I have posted a copy of the first timing gear layout that I plan for this engine.. all critique is welcome .. please have a look and advise .. Thanks again everyone

Regards,

Shiv
 

shiv.brahmi

Website User
Non-VOC Member
Hello everyone,

Please help me with this .. I reasize I might be over ambitious with no technical skills and near 0 resources, but request you all for advise. Please help.

Warm Regards,

Shiv
 

shiv.brahmi

Website User
Non-VOC Member
Hello Clevtrev,

That is correct, however .. Timetraveller did just suggest a few changes .. and I will be changing the design accordingly .. and posting it here soon .. (the oil pump is a geared mechanical .. blue gear and the ones between the cams is the magneto and driver for the advance retard function .. in the picture above) ..

Regards,

Shiv
 

Howard

Well Known and Active Website User
VOC Member
Hello Vince998, Greetings and fair tidings to Germany as well ..

Thank you ever so much for pointing me in the right direction, I've been having sleepless nights over this and now I understand why this information is not to be found anywhere .. probably on account of the fact that it is oh!! so plain a piece of information .. I feel so dumb right now .. but this will be something that I shall never forget .. again Sir appreciate your help .. I am going to begin my CAD drawings .. and will be sharing them if anyone is interested.

Warm Regards,

Shiv

Shiv,

Please don't take offence at this. I admire your enthusiasm, but I think you are currently heading down the road to despair. IF you ever build an engine (with your current knowledge) and IF it runs, there's a 99.9% chance it will be underpowered, rough running and unreliable, and you will have spent hours (probably years) of your life on a project you are not happy with.
Throw your plans in the bin, and if you must build an engine (and I would love to build one) start by learning about how they work, take some engineering lessons, etc - you haven't even started on the joys of metalurgy yet.
Turn your enthusiasm to learning how to make an engine, before you start cutting metal!

Like Sid, I'm a qualified Engineer with 40 years design experience, I have often considered building my own engine using parts from other engines, but while I think I would have a better chance of building a runner, I'm not sure the time and money would be well spent.

Regards

Howard

ps I know it's not a real Vincent, but why not start with a small 2 stroke engine - NSU/Vincent Quickly?
 

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